Alternating-current commutator dynamo-electric machine.



. W. DOINIKOPF. ALTBRNATING CURRENT commumwon DYNAMO ELECTRIC MACHINE.

Patented Dec. 22, 1908.

APPLIOATIOH IILED MAR. 6, 1908.,

w. DOINIKOPF. ALTERNATING CURRENT GOMMUTATOR DYNAMO ELECTRIC MACHINE.

APPLICATION BIL-ED MAR. 6, 1908.

907,578. Patented Dec. 22, 1908.

8 SHEETS-SHEET 2.

Fi .7. B

MTNESSES 6 -ATI'EI Patented Dec. 22, 1908.

APPLICATION FILED MAR. 6, 1908. 907,578.

8 SHEBTSSHEET 3. F159,.

MTNESSES -AITD N EYE w. DOINIKOPF. ALTERNATING CURRENT GOMMUTATOR DYNAMOELECTRIC MACHINE.

APPLICATION TIL ED MAR. 6, 1908.

8 SHEETS-SHEET 2.

' Patented Dec. 22, 1908.

Fig.7.

W. DOINIKOFP.

ALTERNATING CURRENT GOMMUTATOR DYNAMO ELECTRIC MACHINE.

A? IIIIIIIIIIIIIII AB. 6 1 9 0 8. Dec. 22, 8 EEEEEEEEEEEE 6.

W. DOINIKOFF. ALTERNATING CURRENT GOMMUTATOR DYNAMO ELECTRIC MACHINE.

APPLIEATION PI-LED MAR. 6, 199a. Patented Dec 22 1908.

8 SHEETS-SHEET 8' WITNESSES Nygr Jrmg C B W W. DOINIKOFP. ALTERNATINGCURRENT GOMMUTATOR DYNAMO ELECTRIC MACHINE. 907,578.

APPLICATION FILED MAR. 6, 190B Patented Dec. 22, 1908.

8 SHEETS-SHEET 7.

Elk t W. DOINIKOFF.

ALTERNATING CURRENT GOMMUTATOR DYNAMO ELEGTRIG MACHINE.

APPLIUATIQN FILED MAB. 6, 1908. 907,578. Patented Dec. 22, 1908. BSHEETS-SHEET 8.

I [I P\ -ATTU MTNEs 5E5 .1. such as-will enable t UNITED STATES PATENTOFFICE.

WLADIMIR DOINIKOFF, .OF KARLSRU'HE, GERMANY.

ALTERNATING-CURRENT COMMUTATOR DYNAMO-ELEGTBIO MACHINE.

. No. 907,578. Specification of Letters Patent. Patented Dec. 22, 1908.

Application filed March 6, 19oz. seen No. 419,537.

To all whom it may concern: tween the principal armature and the-com- Beit known that I, \NLADIMIR DOINIKOFF, inutator, and a system ofcommutating poles engineer, a subject of the Russian Emperor, which actupon this auxiliary armature. residin at Karlsruhe, 74 KaiserstrassmGer-Whereas, however, the windings of such co many, have invented certainnew and useful poles have been hitherto always inserted in Improvementsin Alternating-Current Comthe principal armature circuit, according tomutator Dynamo-Electric Machines; and I the present invention thewindings of the do hereby declare the followin to be a full,.commutating field are introduced between clear, and exact descri tionof t e invention, points of the principal armature winding on hersskilled in the art a line approximately at right angles to a to which itappertains to make and use the diameter drawn through the connectingsame. point of the corresponding brush.

This invention relates to a device for sup- 1,1 he accompanyingdrawings, Figures 1,

pressing s arking in I alternating current 2 nd 3 are graphic representtion f h ,5 dyna o e ectric hin s hi h rate correction of the commutatorpotential curve with a commutator and is applicable both to which thisinvention seeks to achieve. Figs. single-phase machines and to polyphasema- 4 and 5 are diagrams representing the conchines. nections' of apolyphase commutator motor It has not been possible by means of the orof a rotating field converter in which the 20 devices hitherto known tosuppress to a device according to the invention is used.

sufficient or satisfactory extent the short cir- Figs. 6 and 7 arediagrams representing corcuit currents in the coils undergoingcomresponding different distributions and armutation and consequentsparking at the rangements of the iron in the auxiliary armabru'shes.ture and in the commutating poles. Figs. 8 so 25 Attempts have beenmade, by means of soand 9 are diagrams representing diiierent calledreversing poles, so to modify the comtypes of the auxiliary armaturewinding. mutator potential curve in single phase com- F1 10 shows thecomplete connections of a inutator machines having two brushes that p0yphase commutator motor providedwith the part of the curve correspondingwith the a device according to the invention. Fig. 11

3e position of commutation is flattened so that showsthe connections ofa single phase motor the potential diflerence between the leading havingfour brushes and provided with a deand rear edges of the brush isdecreased as vice according to the invention. Figs. 112,

much as possible. These reversin poles 13, 15 and 16 representcorresponding differhave been arranged in art so that they act outdistributions of the auxiliary armature 35 upon thearmatuie win ingitself, and in part iron and of commutating poles. Fig. 14

4C" tator, All known so. that they act upon an auxiliary armature showsanother singlehase commutator mowinding which may be mounted on asepator having four brus es provided with the rate iron core and isinserted between the device according to the invention. Fig. 17 armaturewinding roperand the commuis a single-phase commutator motor havingdevices of this kind, howthree brushes provided with the device acever,depend for their'action only on dycordin to the invention. Figs. 18 and19 namic induction, and not upon the pulsation show t e distribution ofthe iron of the sysof the magnetic flux, and are conse uently tern ofcommutating poles represented in dependent upon the number of revoutions Fig. 6, with an exciting winding-distributed 45 of the armatureso that while at some speeds upon the yokes of the commutating poles thepotential curve 18 sufliciently flattened and upon the auxiliaryarmature respecor more than sufiiciently flattened, at other tively.Fig. 20 shows the detailed connecspeeds it is not so and consequentlysparking tions for Fig. '18. Fig. 22 shows the like for. still occurs.Fig. 1-9. Figs. Hand 23 representauxiliary 50 The device according tothe present invenarmature windings together with exciting tion does notdepend for its action excluwindings of the commutating oles. Figs.s'ively on the electro-dynamic induction, but, 24. and 25 areconnections wit a distribuon the contrary, principally on the inductiontionof the iron according to Fig. 7 applied to due to pulsation of themagnetic flux. a three-phase frequency converter.

According to the invention there are prov The rotary converter, orvpolyphase comvi'ded an auxiliary armature inserted bemutator motorshown in Figs. 4 and 5 is of a type invented by I-Iutin and Leblanc,andis described, together with its mode of operation, inWechselstromtechnilc, edited by E. Arnold, Berlin, 1904. Said machineconsists of the principal armature A which may be provided with a closedcontinuous current winding of any known form, and to which a threephasecurrent is supplied through the slip rings 8,, S S Bearing on and movingover the commutator C are three brushes B B B from which continuouscurrent can be taken in known manner, since synchronism is establishedbetween the speed of revolution of the brushes and of the rotary field.For this purpose two brushes suffice, but the device according to thepresent invention de scribed is only applicable to such machines as areprovided with at least three brushes. The three-phase current led, bymeans of the slip rings 3,, S 8,, into the main armature winding Aprovides a rotating field, the fun damental wave of which is a sine wave(see Arnolds Wechselstromtechn'ik, Vol. III, pages 295, 300 et seq. inwhich will also be found a discussion of the harmonic waves) and thecommutator potential curve will, in this case, also be a periodic curve,the first harmonic of which is also a sine wave. This said potentialcurve rotates at the same speed as the rotating field, viz.synchronously therewith, and if the armature itself rotates in anopposite direction to the rotation of the commutator potential curve thesaid curve will stand still in space and not rotate relatively to thebrushes. Under these conditions the brushes maintain constantpotentials, wherefore it is possible in such a machine to takecontinuous current from the brushes. It is also possible to obtain thesame effect by making the armature stationary and causing the brushes torotate in the direction of tion of the commutator potential curve and inthis latter case the commutating poles, hereinafter described shouldrotate with the same speed as the brushes. (In connection with this typeof machine, see The Transactions ofthe International Electrical Congressof St. Louis, 1904, article by E. Arnold and J. L. la Cour, TheCommutation of Direct and Alternating Currents).

If the brushes of the machine illustrated in Fig. 4,.move with referenceto the commutator fpotential curve, an alternating current -0 generallylower frequency will be delivered by the machine and the latter becomes,in this case, a frequency converter. Th1? speed of rotation relativelyto the brushes W1 the frequency of the current thus converted will beequal to the slip frequency. As will be apparent, in this case, thecommutator potential curve rotates with a speed relatively differentfrom that of the brushes.

The dotted sine curve C C C, in Fig. 1 is a development ofthefundamental wave of rotavary with the slip of the armature, and.

the commutator potential curve. In proper angular relation with thecurve are arranged the three brushes B B 13,, at equal distances ofl20from each other, and over the points of the brushes are thecommutating P 23 2 1 2: 2 d 22's 2 3 In Fig. 4 the commutating poles areindicated by hatched rectangles and are indicated by the same referenceletters as are used in the preceding paragraph. Since the connectingwires between the principal armature winding A and the commutator C passin front of these commutator poles, electromotive forces are induced insaid wires, the direction-of which is determined by the excitationforthe time being, of the com mutating pole, and these electromotiveforces are added to the electro-motive forces of the corresponding partsof the armature. The form of the commutator potential curve is therebyvaried at the several portions affected, and if it is desired to preventthe establishment of ashort circuit current between the two edges ofeach brush, which, current would give rise to sparking, this deformationof the commutator potential curve must be so controlled that it becomesas shown in Fig. 1 a local flattening of the curve extending on eachside somewhat beyond the edges of the brushes. These flattening-s areshown in Fig. 1 in the curve 0, C C and the difference between theordinates of the normal potential curve shown in dotted lines and thedeformed curve'shown in full lines is a measure of the E. M. F. whichmust be induced with aid of the come mutating poles p, p in theconnecting wires between the armature winding and the commutator inorder to effect the desired fiattenings. These commutating electromotiveforces are'shown carried over upon another abscissae axis in Fig. 2 andappear here as small portions of waves which for neighboring poles p, phave opposite signs for the periods of time shown. Only at the period oftime, at which the axis of the brush passes through the summit of thecommutator potential curve, have both the commutating electromotiveforces the samesign. If in like manner-the corresponding wave portionsfor all the periods of time are indicated on the abscissee axis of Fig.2 and represent the additional electromotive forces in the correspondingtimes and all the summits of these wave portions are connected by anenveloping curve, there are obtained the two curves shown in dottedlincs'in Fig. 2. i The theoretical discussion of the fore-- going showsthat these enveloping curves for a sine-shaped commutator potentialcurve are also sine curves which, however, are displaced with respect tothe commutator potential curve one in leading or forward direction andone in lagging or rearward direction. The excitations of the commutatingpoles must therefore vary approximately in accordance with such anenveloping curve, if they are to induce in the connecting wires betweenthe armature winding and the commutator such cominutating electromotiveforces that the portion of the commutator potential curve, lying betweenthe leading and rear edges of the brushes, is flattened, and in order toobtain this excitation of the commutating poles they are according tothe invention connected in parallel to the brushes and therefore also tothe armature winding, as is shown in Fig. 5. In the application of theconnections shown in Fig. 5 there is involved, however, a small error,since the enveloping curves are not displaced relatively to thecommutator potential curve exactly through 90, but through an angle thesize of which is 90 plus or minus 6, as is shown in Fig. 3.

In order to arrive at as complete a utilization as possible of thecurrents exciting the commutating poles it is essential that themagnetic flux developed in them should as far as possible traverseclosed iron circuit, and for this purpose each of the corresponding polesystems is provided with its own yoke, and the active pole surfacesturned towards the connecting wires between the armature and thecommutator are closed by a se arate auxiliary armature iron core whicmay be keyed on the shaft between the principal armature and thecommutator and may rotate with the armature. For

this system of connnutating poles therefore the arrangement may be asshown in Fig. 6. The poles are closed externally by the yoke J am thepoles by the yoke J, and internally all the po es are closed by theauxiliary armature iron A I In 7 is shown an arrangement of thecommulating iron which yields the same working conditions, but isessentially more sim lo to construct. In this case a substantial yclosed iron circuit for each separate pole is provided through theauxiliary armature A and a separate yoke j,, j, In this constructionthere is for each active polo an additional pole which obviously willact on the connecting wire op ositc to it like the main pole. As,however, t 1e corresponding connnutator segments are not short circuitedby the brushes, the local deformation of the con'nmitator potentialcurve thus prol duced has no practical effect. l

In Figs. 8 and 0 A is the winding of the irincipal armature, thecommutator, B the l brush, and p and p are the corninutat-ing oles. Thetwo figures show different forms of the auxiliary armature winding, thatin Fig. 8 being a drum winding R and that in l Fig. 9 a ring winding R.

If the error indicated in Fig. 3 to be 3 avoided, and if it is desiredto obtain the theoretically correct position of the two envelopin-gcurves as they are shown in Fig. 2, the connecting points for thewindings of the two eommutating poles must be situated at the ends of adiameter or of a chord which is turned relatively to the point ofcontact of the corresponding brush through an angle of 90 plus or minus6, and therefore a proximately through an angle of 90 re atively to therespective commutating pole. Such a branchin cannot be effected at thecommutater itse It may, however, be arrived at if the connection isadopted which is shown in Fig. 10, in which is shown a polyphase seriesor a synchronous motor in which the commutator potential curve rotatesrelatively to the brushes with constant speed,-

egual to the synchronous speed of rotation o the field. This speed isequal to co: ,nC where C is the frequency of the polyphase current. Thisfre uency accords with that of the current ap lied at the brushes whichare connected wit the stator winding of the machine. In this figure theleft-hand part of the connection is a repetition of that in Fig. 5.Instead, however, of connecting the windings of the three commute-tingpairs of oles p, p directly to the inserted between the brushes and thecommutating poles a transformer T shown at the right hand side of thefigure. This trans former has a ring or drum iron core provided with aclosed continuous current winding of known form. The three brushes areconnected in. parallel with this winding at three symmetricallydistributed points 6,, b 1),; it follows that a rotary field is excitedin the iron of the transformer which rotates synchronously with the mainfield of the machine. The connecting points of the winds ings of polesp,, p, are rendered prominent by dotting in the transformer thediameters upon whose ends they are situated and are indicated by thereference letters q, q The connecting points of the windings of theremaining commutating poles are also indicated, but they are not madeseparately rominent because the diagram would then )6 too confused. Fromthis diagram it will be seen that the connectingpoints for the windingsof the res ective commutating poles are situated at tie ends of adiameter which is turned relatively to the point of contact of thecorresponding brush through an angle of 00 plus or minusd". Forinstance, regarding b as the position of brush 3,, with which said pointi) in the winding of the transformer is connected, it will be seen thatthe wires leading to pole p, are connected with the transformer windingat opposite ends of the diameter q, and that the ends of said diameterare displaced 90 plus and minus 6 respectively from point 1). Owing tothis insertion of the transformer T between the brushes and thecommutating poles,

brushes there is the exciting waves or the enveloping placed relative.sentations of the field coils.

curves for both oles of a pair 1), p" are dis l} to each other exactlythrough 180 and the two exciting curves are displaced through exactly 90relatively to the firstharmonic of the commutator po tential curve, thatis to say, the theoretical requirement is fulfilled which can be derivedfrom the local flattening of the coinmutator otentialcurve. The firstharmonic of the exciting curves for the commutating poles thus obtainedare, as already stated, shown dotted in Fig. 2 and the commutating polesexcited according to these curves therefore completely suppress thesource of sparking if the commutator potential curve consists only ofthe indicated sineshaped first harmonic. By this connection moreoverthere is at the same time a part of the higher harmonics taken intoconsideration, namely the higher harmonics of the 2 1 1 order, V beingan even whole number. These are the th, the 9th, the 13th, and so on,that is to say the 4th higher harmonics upwards from the first harmonic.If, however, in any special case the third and the seventh harmonic isstrongly developed, special precautions must be taken for this case inorder that the injurious action on the commutation may be suppressed,and this precaution may consist in using various known connections whichor enfeebling these harmonics. In the case of the 5th, 9th, 13th, etc.harmonics, their peaks extend in the same direction as the peak of thefundamental and therefore the il'ect of the commutating oles on theseharmonies would be generall y similar to that produced with respect tothe fundamental. lhe peaks of the 3rd and 7th harmonics extend in anopposite direction to the peak of the fundamental and it is thereforedesirable to suppress these harmonics. It may be effected by a properdistribution of the main armature winding or by giving proper form tothe pole shoes, or by judicious distribution of the field winding, moreparticularly when the winding is on the stator. A. discussion of thismatter of the harmonics is iven in. llecksclstromtccllnil: hereinbeforereferred to, see page 230 et seq, Vol. VIII, edition. of 1904.

Figs. 11 17 show the application of the device according to thisinvention to-a'selection of known types of single-phasc commutatormotors.

Fig. 11 shows the known connections for a single-phase motor with fourbrushes, Fig. 14' those of another single-phase motor having fourbrushes, and Fig. 17 those of a singlephasemotor having three brushes.what has already been said these connections will be clear withoutfurther explanation, it being understood that the parts marked F inFigs. 11,14 and 17 are conventional repre- The reference are suitablefor suppressing I Frbm i letters indie "te parts which are homologouswith those iii l in the arrangements already described. The i conductorswhich are branched from the brushes, are connected with the transformeri according to the same scheme as that according to which the connectionis made be- I tween the armature and the brushes, so that i in thetransformer winding there is produced a reproduction of the commutatorpotential i curve. When four brushes are used instead (I of three, thereare correspondingly provided four pairs of commutating poles p p andithese are connected with the transformer Iwinding according to the rulegiven. For I the motor in liig. 11 therefore there is used for theconunutating field and the armature 1' iron the arrangement shown in itsclearest l theoretical form in Fig. 12, the simplest pra ctical formbeing that indicated in Fig. 13. For the motor shown in Fig. 14 thecommutating iron maybe as represented in Figs. 13, or 16. For the threebrush motor there may be used for the commutating iron the samearrangement as for the three-phase g commutator motor shown in Fig. 10,this ar- I rangement being indicated in Figs. 6 hnd 7. In order in thiscase to achieve the best possible utilization of the transformer, somepoints of the winding which have equal potentials are connected witheach other, as shown in Fig. .17. According to the theoreticallysimplest arrangement of Figs. 6 and 15, the iron of the commutatingpoles constitutes in connection with the iron of the auxiliary armaturea 1 closed magnetic circuit or several such circuits. When in thesecircuits a flux is created, this may ha men. not merely owing to theexcitation of t 1e windings which are I mounted on the ole coresthemselves, but i by windings whic i may be arranged in any desired partof the magnetic circuit which is l formed by the comm-utating poles withtheir l yoke and the auxiliary armature iron. i As shown in Figs. 18 and20 the exciting windings may be mounted not only on the I commute-tingpoles themselves but on the stationar yokes of the commutating poles Ior upon t 1e rotating auxiliary armature iron, as indicated-in Figs. 19and 22. There are then obtained the arrangements which are 1 shown inFigs. 18 and 19. In Fig. 18, as before, A is the auxiliary armatureiron, J and J are the two *okes, and p 10 p,, and p p are thecommutating p0 es. In Fig. 19 the auxiliary armature iron is distributedthroughout the two rings A,,, A,,. The stationary yokes in Fig. 18 andalso the auxiliary armature irons in Fig. 19 are for the sake ofvclearness shown as rings concentric with each other. In an actualconstruetion these-rings would most simply be of the same diameter and.arranged side by side in different planes. The auxiliary armadicated bythose of like letters connections in a compensated three-phase larmature winding. A

tures are, as hereinbefore indicated, referably located adjacent to andat the en of the principal armature and the circular yokes of theauxiliary poles are of course disposedi relationto the g R between Inthe commutator are disposed as a concentric with and in propercorresponding auxiliary armature ring.

lin

olyphase or single-phase. network. In the atter case only two arenecessary, these beelectrically shifted relatively to each 0t er through180. The connecting wires the main armature winding and drum the Figs.18 and 19 moreoverthe connectingl winding with which the two auxiliary,armapoints of the exciting windings are indicated and marked withreference letters 4-,, e,, 6/2, 81/2, 6,3, ell necting points upon t eperiphery of the winding is wholly free and they may be distributed inrespect to the position of the oles in such a manner that the correctionwith aid of the auxiliary transformer is rendered superfluous.

In the following figures been worked outs Fig. 20 is the diagram ofasynchronous or series commutator motor, rovided with the arrangement ofcommutating les and auxiliary armatures. indicated in Fig. 18. Figs. 21and 23 are diagrammatic representations of the auxiliary armaturewinding, as well as the exciting winding for the case according to Fig.19. Fig. 22 is the scheme of connections for a threehase freuencyconverter which runs wit a speed t at is far removed from synchronismthat is with great slip, in which is employed the particular arrangementof commutating poles and auxilia armatures' hercinbefore described and sown in Fig. 19, it being understood that the auxiliar armatures A and Aare arranged paral el to each other and at the end of the main armature,as diagrammatically indicated in Fig. 19.

In the drawings the reference letters have the following meanings :-A isthe principal is the auxiliary armature, which in some of themodifications described, and as particularly illustrated in Figs. 19,21'and 23 is divided into two parts A and A E W is the exciting windingof the auxiliary armature, which generall is divided into two excitingwindings E Viand E W and acts each upon a part of the armature. In Fig.22 both exciting winds ings E- W and E W for the sake of clearness areshown slightly displaced relatively to each other in order to make theconnecting pgoints visible. C is the commutator, B B

5 the brushes, Pf P'Q Fe 2 P's Pf s are the commutating poles, a a a aren Fig. 22 the branching points of the two exciting windings on the mainarmature winding; in all previous arrangements described these pointsare constituted by the brushes themselves. e e,, e,, e,: e e" are pointswhich indicate the positions of the connectingvpoints of the excitingwindings E W and E with respect to the main armature winding. 5,, 8,, Sare the terminals of a- ,3 It will be seen from this" arrangement thatthe osition of the (3011- I of the drawings, a l number of examples ofthis connection has l tures A and A are wound in common as 2 indicatedin Figs. 20 to 23, inclusive.

Each armature division is provided with an exciting winding E W as inFigs. 21 and 23 which may be simply a spiral winding or as iral wavewinding E W as in Figs. 24 an 25, in which alternate spiral turns aredisposed on adjacent auxiliary armatures.

In connecting these exciting windings E W and E W with the principalarmature windmg, for example, from the point a, of the rincipal armaturewinding wires 0, 0' are ed to the points (2 e, of the two excitingwindings which are respectively forwardly and rearwardly displacedrelatively to the point athrough an angle of in the two pole diagram,see Figs. 22 and 23. The remaining connections are similarly formed. Inthe case of a single-phase alternating current frequency converter or ofan alternatingcontinuous current converter two brushes in a two polediagram suffice, and the com mutating poles must also be correspondinglyarranged over the brushes. In this manner rotating or pulsatin magnetomotive force curves are induced in the two auxiliar armatures or yokes,which curves are disp aced relatively to each other through 180 inspace.

Figs. 24 and 25 show the connection of a frequency converter providedwith the device according to the invention, the ipeed o revolution beingany that is desire The armature parts A,, and A are each subdivided intoarts A A A Q AQ as indicated in *ig. 25. The auxiliary armature windingR is a spiral wave winding not closed on itself of which the coils arewound alternately according to the series to which they belong upon thetwo armature )arts A A A A The number of the armature divisions may alsobe increased, in which case the coils of the auxiliary armature windingmust be correspondingly dis tributed.

The exciting windings E W and E W are constructed as closed-coil spiralor progressive helical windings, of which the coils are subdivided tocorrespond with those of the auxiliary armature winding each upon two ormore armature divisions. The connect-' in oints of these windings arearranged re atively to the branching points of the main armature windingas shown in Figs. 21 and 22, that is to say, the are displacedrelatively to the said branc ling oints one in forward and one inrearwarr direction through an angle of 90. The connections of machinesfor iron core upon which the referred to are clearly indicated in, Figs.24 and 25.

By the subdivision of the auxiliary armature winding and thedistribution of the separate coils is achieved the result that only onecoil of the auxiliary armature winding as well as one of the excitingwindings comes simultaneously beneath a commutating pole and thuspulsations of the magnetic flux are almost undamped in the region of thepoles.

'lhe commutating poles are constructed accordin to Fig. 9, but itis nolonger necessary to ave a gap between each commutating pole and itsneighboring pole, and both are brought together, which is permissible asthey are not wound. Ihe commutating poles may be subdivided into partsp,, p,, p p,, correspondingly with the the divisions of the armature. Inthis arrangement the flattening eliect of the commutating poles is quiteindependent of the number of revolutions of the machine. For this reasonthe arrangement is applicable for fiequency converters and various kindsconverting alternating current into continuous current. i

In order to avoid-an injurious effect of the dynamic induction upon thecommutating process in the arrangement according to Figs. 20 and 22, itis necessary that the commutating poles cover a sufficient number ofexciting coils suitably separated from each other.

In multipolar machines it is advantageous in all arrangements accordingto the inVen-' tion to distribute the commutating poles as uniformly aspossible at the periphery of the auxiliary armature.

The auxiliary armature windings shown in Figs. 21, 23 and 25 areapplicable without any further alteration save the omission of theexciting windings for machines at whose brushes there is an alternatingtension of high periodicity at all loads, that is to say for example forcompensated asynchronous machines and single phase commutator motors.

What I claim is l. Mechanism for preventing sparking at the brushes ofalternating current commutator dynamo electric machines having a mainarmature winding, a commutator, and connecting wires between saidwinding and the commutator; comprising an auxiliary said connectingwires are wound, eommutating poles adapted to influence the saidconnecting wires in such manner that the commutator potential curve atthe places where the brushes are situated is flattened, windings toexcite said commutating poles, and an energizing circuit for said poleexciting windings inv derivation of the commutator brushes.

2. Mechanism for preventing sparking at the brushes of alternatingcurrent commu- 1 tator dynamo electric machines having a i main armaturewinding,

connecting Wires between said winding and 1 the commutator; comprisingan auxiliary iron core upon which the said connecting wires are wound,commutating poles adapted to influence the said connecting wires in suchI manner that the commutator potential curve at the places where thebrushes are situated is flattened, windings to excite the saidcommutating poles, and an exciting circuit for I said pole excitingwindings in derivation of the commutator brushes, the connections of thesaid windings with the exciting circuit being situated each between twopoints of I the said exciting circuit I lie in aline approximately atright angles to a diameter through the connecting point of thecorresponding brush.

3. Mechanism for preventing sparking at the brushes of alternatingcurrent commutator dynamo electric machines, comprising commutatingpoles, exciting windings for said commutating poles, a transformer, acontinuous current winding on said transformer, the said transformerbeing situated between the brushes and the-windings of the commutatinpoles, connections between the Winding 0' the said transformer and thebrushes, and connections between the windings of said transformer andthe exciting windings for the commutating poles, the said latterconnections lying between the ends of chords which are turned through anangle of increased or diminished to the extent of approximately asegment breadth plus half a brush breadth from the axes of the brushesrelatively to the connecting points of the brush connections.

4. Mechanism for preventing sparking at l the brushes of alternatingcurrent commutator dynamo electric machines having a mainarmaturewinding, a commutator, and connecting wires between said-windings and lthe commutator comprising an auxiliary armature iron core upon which thesaid connecting wires are wound, commutating poles i adapted toinfluence the said connecting l wires in such manner that the commutatorpotential curve at the places where the brushes are situated isflattened, windings for exciting said commutating poles, an excitingcircuit for said pole exciting windings in derivation of the commutatorbrushes, the A connections of the said windings with the excitingcircuit being situated each between two points of the exciting circuitso selected that they lie in a line approximately at right angles to theconnecting point of the corresponding brush, and means for completingthe magnetic circuitof each commutator pole through the auxiliaryarmature iron.

5. Mechanism for preventing sparking at the brushes of alternatingcurrent commul tator dynamo electric machines, comprising a commutator,and

so selected that they commut ating poles, exciting windings for saidcommutating poles, a transformer situated between the brushes and thewindings of said cornmutating poles, a continuous current winding onsaid transformer, connections between the windings of said transformeran the brushes, connections between the windings of said tranformer andthe windings of the commutating poles, said latter connections lyingbetween the ends of chords which are turned through an angle of 90increased or diminished to the extent of a proximately half a segmentbreadth plus half a brush breadth from the axes of the brushesrelatively to the connecting points of the brush connections, and meansfor completing the magnetic circuit of each commutating pole through theauxiliary armature iron.

6. Mechanism for preventing sparking at the brushes of alternatingcurrent commutator dynamo electric machines having a main armature, awinding on said armature, a commutator, and wires connecting the saidarmature winding and the commutator; comprising an auxiliary armatureiron core upon which said wires are wound, commutating poles, a yoke forthe said commutating poles, a sub-divided winding serving to excite saidcommutating poles, and an energizing circuit for said sub-dividedwinding in derivation of the commutator brushes.

In testimony whereof I have affixed my signature, in presence of twowitnesses.

WLADIMIR nonuxorr.

Witnesses Rrormnn RISKUER, Jos. H. LEUTE.

